RBG-16-829, Forwards Response to Core Performance Branch Draft SER Open Items Re post-irradiation Monitoring Program & Inadequate Core Cooling (NUREG-0737,Item II.F.2).Indicated Responses Will Be Included in Future FSAR Amend

Forwards Response to Core Performance Branch Draft SER Open Items Re post-irradiation Monitoring Program & Inadequate Core Cooling (NUREG-0737,Item II.F.2).Indicated Responses Will Be Included in Future FSAR Amend

ML20079M274
Person / Time
Site:	River Bend
Issue date:	01/20/1984
From:	Booker J GULF STATES UTILITIES CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.2, TASK-TM RBG-16-829, NUDOCS 8401270245
Download: ML20079M274 (6)

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~ h GULF STATES UTILITIES COMPANY Post OFF1CE HOx 2951 . BEAUMONT. TEXA9 77704 A RfA CODE 409 8 38 6631 January 20, 1984 RBG- 16,829 r File Code G9.5, G9.8.6.1 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Mr. Denton:

River Bend Station Units 1 and 2 Docket Nos. 50-458/50-459 Enclosed for your review are Gulf States Utilities Company responses to Draft Safety Evaluation Report (DSER) open items identified by the Nuclear Regulatory Commission's Core Performance Branch (CPB). This letter supplements information contained in docheted correspondences from J.E. Booker to H.R. Denton dated November 11, 1983 and December 30, 1983. Attachment 1 summarizes the open items and indicates changes to be made in the River Bend Station FSAR. Attachment 2 provides the response and reference material for each item. Where indicated, these responses will be provided in a future amendment to the FSAR.

Sincerely,

, I-

) J.E. Booker i Manager - Engineering Nuclear Fuels & Licensing River Bend Nuclear Group JEB/N / JE 2.c.losures e401270245 Q h$g PDR ADOCK pDR E

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ATTACHMENT 1 DSER SECTION SUBJECT FSAR REVISI0riS 1

4. 4.2.4.3 Post Irradiation Monitoring N/A pg. 4-29 Program 10, 4.4.7 Inadequate Core Cooling Enclosure 1 pg. 4-44,47 (LRG II 6-CPB; TMI Item II.F.2) l

q-ATTACHMENT 2

4. DSER (page 4-29) - Post Irradiation Monitoring Program

Response

River Bend Station will commit to implemer.' a fuel surveillance program that will meet the intent of Paragraph II.D.3 of Section 4.2 of the SRP la a manner acceptable to the staff prior to full power operation.

l. 10. DSER (page 4-44, 4-47) - Inadequate Core Cooling (II.F.2)

Response

The response to this request is provided in the December 30, 1983 letter from J.E.. Booker to H.R. Denton and supplemented in Enclosure 1.

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RBS FSAR up QUESTION 421.014 (7.2, 7.3, 7.4, 7.5) 7.v/

Provide an evaluation of the effects of high temperatures on reference legs of water level measuring instruments subsequent to high-energy line breaks, including the potential for reference leg flashing / boil- off, the indication / annunciation available to alert the' control room

. operator of erroneously high vessel level indications resulting from high temperatures, and the effects on safety systems actuation (e.g., delays).

4 RESPONSE .

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Th; re sp;r.ch tg tifi rcqac;t will bc pretided by

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REPLACE WITH INSERT -

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- ' Amendment 9 . Q&*1 7.2-2 July 1983 fff e

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};r INSERT (for Pg. QSR 7.2-2)

A comprehensive report discussing the effects of high temperatures on water level reference legs for BWR water level instrumentation

-has been submitted to the NRC Staff for review by the BWR Owners' Group. The report is entitled " Review of BWR Reactor Vessel Water Level Measurement Systems" and is identified as S. Levy Report No.

SLI-8211. River Bend Station endorses the content and findings of this report where applicable to the design of RBS Unit 1.

will be ThefollowingdesignfeaturesE4ae>implementedatRiverBendStation j

, to improve control room operator and safety system response where Prior to accurate reactor vesse'l water level measurements'are required: . fuel load

1) The vertical drop of the water level reference leg instrument lines does not exceed eighteen inches where the lines are subject to temperature excursions capable of causing erroneous readings. The area of primary concern for this design improvement is the drywell.

RBS procedures delineate for cperator information the maximum expected errors for water level measurements given the unlikely event of drywell heatup beyond normal ambient conditions.

g 2) Annunciation is provided in the main control room to alert the operator to potential or actual water level measurement anomolies owing to high reference / variable leg temperatures.

The annunciator is synthesized from two, redundant, Class 1E instrument channels which monitor,drywell temperature.

3) The control room operator is furnished with redundant, Class 1E reactor vessel water level instrument channels for two overlapping regions of the vessel. The first region covers water level over a wide range from the dryer down to near the top of the fuel zone. The second region overlaps the first but extends down to the bottom of the core region. This safety-related display instrumentation and other water level measurement readings are deemed sufficient to provide the operator with an accurate appraisal of reactor vessel water level.

,, , 4) ECCS initiating signals are generated from analog circuitry which provides a switching function. Water level instruments 17-4( used for ECCS actuation are grouped according to range (narrow, wide, fuel zone, and high level-upset) and electrical channel separation. This allows individual instrument channels to be observed for proper operation. This design feature greatly reduces the possibility of either a failed channel being unnoticed or erroneous channel information being used for system actuation.

ki 5) Reactor water level information from several sources within the main control room is monitored by the Safety Parameter Display System (SPDS). The SPDS alerts control room operators to water level measurement anomolies should the situation arise. The

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-SPDS performs this function by performing a channel check by

. comparing two or more channels for equivalence within a given

. error margin.

6. River Bend Station utilizes restriction orifices in the variable and reference leg sensing lines for RPV water level measurements. The orifices are located in close proximity to the drywell instrument penetrations. This design feature effectively obviates oscillatory water level readings when flashing occurs in the drywell portion of sensing lines.

Additional information is provided in revised Section 7.5.1.1.2 and Appendix 1A, Item II.F.2.

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